Great post. I’d add one more thing: Production.
For the conferences I organise, I always insist on presentations a week beforehand, if they’re to talk to a slide deck, and often go back to a speaker and ask them to tweak it. My job as a conference producer is to produce the speakers and ensure they give the best show possible. It’s a job I love doing: getting the best out of a speaker and ensuring they feel happy with the result. Nobody wants to do a poor speaking gig, after all.
(One of the conferences I organise is Next Radio).